(Cat? OR feline) AND NOT dog?
Cat? W/5 behavior
(Cat? OR feline) AND traits
Cat AND charact*

This guide provides a more detailed description of the syntax that is supported along with examples.

This search box also supports the look-up of an IP.com Digital Signature (also referred to as Fingerprint); enter the 72-, 48-, or 32-character code to retrieve details of the associated file or submission.

Concept Search - What can I type?

For a concept search, you can enter phrases, sentences, or full paragraphs in English. For example, copy and paste the abstract of a patent application or paragraphs from an article.

Concept search eliminates the need for complex Boolean syntax to inform retrieval. Our Semantic Gist engine uses advanced cognitive semantic analysis to extract the meaning of data. This reduces the chances of missing valuable information, that may result from traditional keyword searching.

Publishing Venue

Related People

Abstract

RF plasmas of oxygen and fluorine are commonly used to remove epoxy drill smear from through holes on printed circuit boards. Achieving uniform plasma etch rates, especially for large boards or multiple standard size panels in close proximity, can be difficult. A method for achieving uniform etch rates is described in the following. The primary etch species used are atomic oxygen and atomic fluorine. For a given amount of atomic oxygen in the plasma, there is an optimum amount of atomic fluorine required to achieve a maximum etch rate. Fluorine atoms in small concentrations enhance etch rates through reactions which generate radical surface sites. Fluorine present in excess, however, inhibits etching through competition with O atoms for sites leading to the formation of fluorocarbon compounds on the surface.

Country

United States

Language

English (United States)

This text was extracted from a PDF file.

At least one non-text object (such as an image or picture) has been suppressed.

This is the abbreviated version, containing approximately
52% of the total text.

Page 1 of 2

Etch Rate Uniformity Enhancement for Plasma Drill Smear Removal

RF plasmas of oxygen and fluorine are commonly used to remove epoxy drill
smear from through holes on printed circuit boards. Achieving uniform plasma
etch rates, especially for large boards or multiple standard size panels in close
proximity, can be difficult. A method for achieving uniform etch rates is described
in the following. The primary etch species used are atomic oxygen and atomic
fluorine. For a given amount of atomic oxygen in the plasma, there is an
optimum amount of atomic fluorine required to achieve a maximum etch rate.
Fluorine atoms in small concentrations enhance etch rates through reactions
which generate radical surface sites. Fluorine present in excess, however,
inhibits etching through competition with O atoms for sites leading to the
formation of fluorocarbon compounds on the surface. Hence, the concept of
optimum ratio of atomic concentrations of O and F ([O]/[F]) is fundamental to
uniform etching. In addition, the etching process consumes relatively more
fluorine than oxygen, resulting in an increase in O/F. Achieving uniform etch
rates in the through holes across a panel is a major concern. Typically,
nonuniform etching is characterized by positions near the perimeter of the board
etching at higher rates than positions near the center of the board. This is due to
consumption of etching species resulting in a concentration gradient across the
board. One means of compensating for this depletion of species is to use a feed
gas composition that is rich in fluorine. The excessive atomic fluorine
concentration produces a fluorine rich mixture at the edge of the board (low [O]/[F]). As etchant is consumed toward the center of the board, O/F increases
toward a more optimum value. Hence...